The known touch panel is made by forming an inducing area on one surface of the substrate. Touch control is available in the inducing area by inducing human fingers or signals from a stylus. Most materials used in the inducing area are transparent conductive film (e.g. Indium Tin Oxide ITO). It makes users to perform touch control in operation by touching the conductive film where corresponds to a screen on the display.
Currently, commonly applied principles for touch control are resistive type, capacitive induced type, infrared induced type, electromagnetic induced type, sonic induced type, etc. Operation of the capacitive induced type touch panel is to utilize changes of capacitance generated by combination of static electricity arranged between transparent electrodes and human body. Coordinates of the touched position can be detected by the generated induced current. Since the capacitive induced type touch panel has better advantages in the field of transmittance, hardness, accuracy, response time, lifecycle of touch, operating temperature, and initiating force, therefore, it is wildly adopted.
In order to detect a position on the touch panel where the user uses a finger or a stylus to touch, a number of induced capacitance type touch inducing techniques have been developed in the industry. For example, in the U.S. Patent Publication No. 2012/0256642, a single-layered touch inducing system is disclosed and can be used to detect a touch position on a touch inducing surface. The single-layered touch inducing system includes conductor assemblies in two axes. The two axes are perpendicular to each other. The first axial conductor assemblies are composed of a number of first conductor cells linked to each other. The second axial conductor assemblies are composed of a number of second axial conductor cells linked by wires. A proper distance is reserved between adjacent conductor cells in different axes. Each conductor assembly is electrically linked to a corresponding wire, further linking to a control circuit. The control circuit causes an induced electric field in an adjacent range near adjacent conductor cells in different axes by providing signals to the two conductor assemblies in different axes through wires. If users touch the adjacent range, an equivalent capacitance value of the induced electric field will be changed. A touch position of the user can be reckoned by the amount of change of the capacitance value. A shape of the conductor cell is like a letter E or a ring.
In the R.O.C. Patent No. 1457813, a single-layered capacitive touch panel is disclosed. Comparing with the U.S. Patent Publication No. 012/0256642, they both utilize induced electric field in the adjacent regions between different axis conductor cells and reckon a touch position of the user by the amount of changes of the capacitance value. The difference is that the present patent uses a tooth structure for the adjacent regions between different axis conductor cells.
In the U.S. Pat. No. 8,502,796, a capacitive touch panel is disclosed. A feature of the capacitive induced layer is that the second axial conductor cell is composed of bar shape figures in different lengths, so that a distribution of the induced electric field has different strengths. The distribution of the induced electric field in a central region uses longer bar shape figures which leads to a stronger electric field. The distribution of the induced electric field in the peripheral regions uses shorter bar shape figures which leads to a weaker electric field. Because the electric field has strength differences, change amount of the induced capacitance values are different when users touch the central electric field and the peripheral electric field, respectively. Hence, the induced range of the electric field can be increased and the touch position can be reckoned. The structure has an effect to improve the distribution of the electric field and increase sensitivity of induction and saves the number of used wires. Meanwhile, complexity of the control circuit can be reduced.
In the R.O.C. Utility Patent No. M447541, a capacitive touch panel is disclosed. A feature of the capacitive induced layer is that the conductor cells and wires are not formed in non-linear geometry. The transmittance of the conductor cells and wires on the touch panel can be improved, further improving the display effect of the display panel.
Reviewing the patents and applications mentioned above, the U.S. Patent Publication No. 2012/0256642, the R.O.C. Invention Patent No. 1457813 and the R.O.C. Utility Patent No. M447541 have disclosed many geometric shapes for every conductor cells. However, the induced electric fields are not distinguished according to the strength. Therefore, the size of the conductor cells is limited by the touch area of the user. The conductor cells in the U.S. Pat. No. 8,502,796 are composed of bar shape figures in different lengths, causing a distribution of different strengths for the induced electric field. Thus, area of the conductor cells and the induced range of the electric field can be increased and the touch position can be reckoned. However, the distribution of the electric field is asymmetric. Errors will occur if the touch position is calculated by a general rule while complexity and calculating time of the control circuit will increase if special calculation is adopted.
Hence, the induced range of the electric field needs to be increased and the techniques for symmetric distribution of the electric field are required for the induced layer of the touch panel. Not only the induced range of the conductor cells is increased, but the amount of wires is reduced. Meanwhile, increase of complexity and calculating time of the control circuit can be avoided.